Proxy config affecting change events

[guicassolato]

What this PR does / why we need it:

It defines a new event to be issued whenever an object that is part of a proxy config changes (or gets created, or destroyed). This event will asynchronously touch a tracking record in a separate table, also introduced, that holds a 1-1 relationship with proxy.

Which issue(s) this PR fixes

This will make possible for the UI to highlight for the user a potential outdated proxy config, thus being relevant to #1235.

Closes THREESCALE-3555

TODOs

• Create table to store the change history on proxy config affecting objects
• Generate the schema for Oracle and PostgreSQL
• Define a new type of event to be issued whenever a proxy config affecting change occurs (plus subscriber and worker)
• Issue the event on every model of proxy config affecting object (in a after_commit, for each proxy potentially affected)
  • ProxyRule (Metric deletion will kick ProxyRule deletion, so already covered)
  • Policy
  • Proxy (Maybe only a few attributes – policies_config)
  • GatewayConfiguration

Special notes for your reviewer
Not sure if we should issue one event per proxy (passing proxy and affecting object) or just one event per change, passing only the affecting object and let the creation of the event to handle the logics of triggering one background job per proxy. In the latter case, the event would have to be aware of the different types of affecting objects (so it can get to the proxies).

To sum up (very roughly exemplifying):

Option A

# where the event is triggered (many places in the code) 
Event.new(object)

# what the event does
for each proxy using object
  Notifier.new(proxy, object)

Option B

# where the event is triggered (many places in the code) 
for each proxy using object
  Event.new(proxy, object)

# what the event does
Notifier.new(proxy, object)

Update: going with Option B.

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I won't tag this as APIAP-only because I think this can be used for non-APIAP accounts as well.

[codecov]

Codecov Report

Merging #1244 into master will decrease coverage by 0.99%.
The diff coverage is 99.17%.

@@           Coverage Diff            @@
##           master   #1244     +/-   ##
========================================
- Coverage    93.1%   92.1%     -1%     
========================================
  Files        2487    2413     -74     
  Lines       82372   79114   -3258     
========================================
- Hits        76693   72870   -3823     
- Misses       5679    6244    +565

Impacted Files	Coverage Δ
test/unit/proxy_test.rb	100% <100%> (ø)	⬆️
.../subscribers/proxy_config_event_subscriber_test.rb	100% <100%> (ø)
...ts/proxy_configs/affecting_object_changed_event.rb	100% <100%> (ø)
...rkers/proxy_config_affecting_change_worker_test.rb	100% <100%> (ø)
...pp/workers/proxy_config_affecting_change_worker.rb	100% <100%> (ø)
app/lib/event_store/repository.rb	100% <100%> (ø)	⬆️
...oxy_configs/affecting_object_changed_event_test.rb	100% <100%> (ø)
app/lib/proxy_config_affecting_changes.rb	100% <100%> (ø)
app/models/proxy.rb	97.74% <100%> (+0.07%)	⬆️
app/models/proxy_rule.rb	98.63% <100%> (+0.01%)	⬆️
... and 217 more

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[hallelujah]

Suggested change

	return if changes_attributes.include?('created_at')
	return if created_at_changed? || (changes_attributes & PROXY_CONFIG_AFFECTING_ATTRIBUTES).empty?

[guicassolato]

No, it's not changed_attributes, it's changes_attributes, a variable defined in the line before.

[hallelujah]

Using this method (probably in the view) creates records right?
If yes, can we avoid that somehow?

[guicassolato]

Well, if we have a proxy config, then we can also have an affecting change history I think. It also saves us from having to migrate data.

[hallelujah]

fair enough

[thomasmaas]

Still needs the schema for Oracle and PostgreSQL though

[hallelujah]

So you can use previously_changed? https://github.com/3scale/porta/blob/d21f8d5e7a6dc740db6652e0604dcf0b639edb52/lib/previously_changed.rb

[hallelujah]

So you can use previously_changed? https://github.com/3scale/porta/blob/d21f8d5e7a6dc740db6652e0604dcf0b639edb52/lib/previously_changed.rb

Which will be introduced in rails 5.0